Cutting balloon catheter

ABSTRACT

A medical balloon catheter including a catheter shaft and an inflatable balloon secured to a distal portion of the catheter shaft. One or more cutting blades are secured to the inflatable balloon by a first polymeric adhesive material forming a mounting pad encasing a base portion of the cutting blade therein, and a second polymeric adhesive material adhesively bonding the mounting pad to a surface of the balloon. The first polymeric adhesive material has a first ductility and the second polymeric adhesive material has a second ductility greater than the first ductility.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/336,654, filed Dec. 23, 2011, now U.S. Pat. No.8,491,615, which claims priority to U.S. Provisional Patent ApplicationNo. 61/428,107, filed on Dec. 29, 2010, the entire disclosures of whichare incorporated herein by reference.

TECHNICAL FIELD

The disclosure pertains to angioplasty balloon catheters having cuttingelements mounted onto an angioplasty balloon. More particularly, thedisclosure is directed to adhesively bonding cutting blades to anangioplasty balloon.

BACKGROUND

Heart and vascular disease are major problems in the United States andthroughout the world. Conditions such as atherosclerosis result in bloodvessels becoming blocked or narrowed. This blockage can result in lackof oxygenation of the heart, which has significant consequences sincethe heart muscle must be well oxygenated in order to maintain its bloodpumping action.

Occluded, stenotic, or narrowed blood vessels may be treated with anumber of relatively non-invasive medical procedures includingpercutaneous transluminal angioplasty (PTA), percutaneous transluminalcoronary angioplasty (PTCA), and atherectomy. Angioplasty techniquestypically involve the use of a balloon catheter. The balloon catheter isadvanced over a guidewire so that the balloon is positioned adjacent astenotic lesion. The balloon is then inflated, and the restriction ofthe vessel is opened.

One of the major obstacles in treating coronary artery disease and/ortreating blocked blood vessels is re-stenosis. Evidence has shown thatcutting or scoring the stenosis, for example, with an angioplastyballoon equipped with a cutting element, during treatment can reduceincidence of re-stenosis. Additionally, cutting or scoring the stenosismay reduce trauma at the treatment site and/or may reduce the trauma toadjacent healthy tissue. Cutting elements may also be beneficialadditions to angioplasty procedures when the targeted occlusion ishardened or calcified. It is believed typical angioplasty balloons,alone, may not be able to expand certain of these hardened lesions.Thus, angioplasty balloons equipped with cutting elements having cuttingedges have been developed to attempt to enhance angioplasty treatments.There is an ongoing need for improved structures and methods of mountingcutting elements, such as cutting blades onto an inflatable angioplastyballoon of an angioplasty balloon catheter.

SUMMARY

The disclosure is directed to several alternative designs, materials andmethods of manufacturing medical device structures and assemblies.

Accordingly, one illustrative embodiment is a medical balloon catheterincluding a catheter shaft and an inflatable balloon secured to a distalportion of the catheter shaft. At least one cutting blade is secured tothe inflatable balloon by a first polymeric adhesive material forming amounting pad encasing a base portion of the cutting blade therein, and asecond polymeric adhesive material adhesively bonding the mounting padto a surface of the balloon. The first polymeric adhesive material has afirst ductility and the second polymeric adhesive material has a secondductility greater than the first ductility.

Another illustrative embodiment is a medical balloon catheter includinga catheter shaft and an inflatable balloon secured to a distal portionof the catheter shaft. The catheter shaft includes an inflation lumen influid communication with the inflatable balloon. A cutting bladeincluding a cutting edge and a base portion opposite the cutting edge ismounted to the balloon by a first polymeric adhesive material forming amounting pad encasing the base portion of the cutting blade therein, anda second polymeric adhesive material adhesively bonding the mounting padto a surface of the balloon. The mounting pad includes a bottom surfaceand first and second opposing side surfaces. A first portion of thesecond polymeric adhesive material is interposed between the bottomsurface of the mounting pad and the surface of the balloon, and secondand third portions of the second polymeric adhesive material contact thefirst and second opposing side surfaces of the mounting pad,respectively.

Yet another illustrative embodiment is a method of securing a cuttingblade to a balloon of a balloon catheter. The method includes molding amounting pad formed of a first polymeric adhesive material about a baseportion of a cutting blade, such that base portion of the cutting bladeis encased in the mounting pad. The mounting pad, with the base portionof the cutting blade encased therein, is then adhered to a surface of aballoon with a second polymeric adhesive material having a ductilitygreater than the first polymeric adhesive material.

The above summary of some example embodiments is not intended todescribe each disclosed embodiment or every implementation of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a partial cross-sectional side view of an exemplary cuttingballoon catheter disposed in a blood vessel;

FIG. 2 is a transverse cross-sectional view of an inflatable balloon ofa balloon catheter having a plurality of cutting elements mountedthereon;

FIG. 3 is a cross-sectional view of an exemplary arrangement of acutting element mounted to a balloon of a balloon catheter;

FIG. 4 is a cross-sectional view of another exemplary arrangement of acutting element mounted to a balloon of a balloon catheter;

FIG. 5 is a cross-sectional view of another exemplary arrangement of acutting element mounted to a balloon of a balloon catheter;

FIG. 6 is a top view of another exemplary arrangement of a cuttingelement mounted to a balloon of a balloon catheter;

FIG. 6A is a cross-sectional view of the arrangement of FIG. 6 takenalong line 6A-6A;

FIG. 6B is an enlarged top view of a portion of the arrangement of FIG.6; and

FIGS. 7-12 illustrate an exemplary method of mounting a cutting elementto a balloon of a balloon catheter.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit aspects of the invention tothe particular embodiments described. On the contrary, the intention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

As used in this specification and the appended claims, the term“ductility” refers to the ability of a material to be plasticallydeformed by elongation without fracture. Ductility of a material istypically measured as a percentage increase in length at fracturecompared with its original length and is termed percent elongation.

As used in this specification and the appended claims, the term “lower”refers to a portion facing toward the central longitudinal axis and theterm “upper” refers to a portion facing away from the centrallongitudinal axis.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the invention. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

FIG. 1 is a partial cross-sectional side view of an example catheter 10disposed in a blood vessel 12 and positioned adjacent an intravascularlesion 14. The catheter 10 may include a balloon 16 coupled to acatheter shaft 18. One or more cutting members or blades 20 may bemounted on the balloon 16. In general, the catheter 10 may be advancedover a guidewire 22, through the vasculature, to a target area. Oncepositioned at the target location in the vasculature, the balloon 16 canbe inflated to exert a radially outward force on the lesion 14, as thecutting members 20 engage the lesion 14. Thus, the cutting members 20may cut or score the lesion 14 to facilitate enlarging the lumenproximate the lesion 14. The target area may be within any suitableperipheral or cardiac vessel lumen location.

The cutting members 20 may vary in number, position, and arrangementabout the balloon 16. For example, the catheter 10 may include one, two,three, four, five, six, or more cutting members 20 that are disposed atany position along the balloon 16 and in a regular, irregular, or anyother suitable pattern. For example, in some embodiments the balloon 16may include a plurality of cutting members 20 longitudinally arrangedsymmetrically around the circumference of the balloon 16.

The cutting members 20 may be made from any suitable material such as ametal, metal alloy, polymer, metal-polymer composite, and the like, orany other suitable material. For example, cutting members 20 may be madefrom stainless steel, titanium, nickel-titanium alloys, tantalum,iron-cobalt-nickel alloys, or other metallic materials in someinstances.

The balloon 16 may be made from typical angioplasty balloon materialsincluding polymers such as polyethylene terephthalate (PET),polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE),polybutylene terephthalate (PBT), polyurethane, polyvinylchloride (PVC),polyether-ester, polyester, polyamide, elastomeric polyamides, polyetherblock amide (PEBA), as well as other suitable materials, or mixtures,combinations, copolymers thereof, polymer/metal composites, and thelike.

The balloon 16 may be configured so that the balloon 16 includes one ormore “wings” or wing-shaped regions when the balloon 16 is deflated. Insome instances, the wings may be configured so that the cutting members20 can be positioned at the inward-most positions of the deflatedballoon 16, with cutting members 20 enfolded under the wings of theballoon 16. This arrangement may reduce the exposure of the cuttingmembers 20 to the blood vessel during delivery of the balloon 16 to thelesion 14.

The shaft 18 may be a catheter shaft, similar to typical cathetershafts. For example, the catheter shaft 18 may include an outer tubularmember 26 and an inner tubular member 24 extending through at least aportion of the outer tubular member 26. Tubular members 24/26 may bemanufactured from a number of different materials. For example, tubularmembers 24/26 may be made of metals, metal alloys, polymers,metal-polymer composites or any other suitable materials.

Tubular members 24/26 may be arranged in any appropriate way. Forexample, in some embodiments the inner tubular member 24 can be disposedcoaxially within the outer tubular member 26. According to theseembodiments, the inner and outer tubular members 24/26 may or may not besecured to one another along the general longitudinal axis of thecatheter shaft 18. Alternatively, the inner tubular member 24 may followthe inner wall or otherwise be disposed adjacent the inner wall of theouter tubular member 26. In other embodiments, the tubular members 24/26may be arranged in another desired fashion.

The inner tubular member 24 may include an inner lumen 28. In at leastsome embodiments, the inner lumen 28 is a guidewire lumen for receivingthe guidewire 22 therethrough. Accordingly, the catheter 10 can beadvanced over the guidewire 22 to the desired location. The guidewirelumen 28 may extend along essentially the entire length of the cathetershaft 18 such that catheter 10 resembles traditional “over-the-wire”catheters. Alternatively, the guidewire lumen 28 may extend along only aportion of the catheter shaft 18 such that the catheter 10 resembles“single-operator-exchange” or “rapid-exchange” catheters.

The catheter shaft 18 may also include an inflation lumen 30 that may beused, for example, to transport inflation media to and from the balloon16 to selectively inflate and/or deflate the balloon 16. The locationand position of the inflation lumen 30 may vary, depending on theconfiguration of the tubular members 24/26. For example, when the outertubular member 26 surrounds the inner tubular member 24, the inflationlumen 30 may be defined within the space between the tubular members24/26. In embodiments in which the outer tubular member 26 is disposedalongside the inner tubular member 24, then the inflation lumen 30 maybe the lumen of the outer tubular member 26.

The balloon 16 may be coupled to the catheter shaft 18 in any of anumber of suitable ways. For example, the balloon 16 may be adhesivelyor thermally bonded to the catheter shaft 18. In some embodiments, aproximal waist 32 of the balloon 16 may be bonded to the catheter shaft18, for example, bonded to the distal end of the outer tubular member26, and a distal waist 34 of the balloon 16 may be bonded to thecatheter shaft 18, for example, bonded to the distal end of the innertubular member 24. The exact bonding positions, however, may vary.

FIG. 2 is a transverse cross-sectional view showing one possiblearrangement of cutting members or blades 20 mounted to the balloon 16.While the balloon 16 is shown having four cutting members 20 mountedthereon, in other embodiments, the balloon 16 may include one, two,three, five, six, seven, eight, or more cutting members 20. The cuttingmembers 20 may be symmetrically or asymmetrically spaced around thecircumference of the balloon 16. The cutting members 20 may include abase portion 36 and a cutting edge 38 opposite the base portion 36extending radially outward from the balloon 16.

The cutting members 20 may be secured to the outer surface of theballoon 16 by encasing the base portion 36 of the cutting member 20 in amounting pad 40 formed of a first polymeric adhesive material 41, andadhesively bonding the mounting pad 40, with the base portion 36 of thecutting member 20 embedded therein, to the outer surface of the balloon16 with a second polymeric adhesive material 42 forming a base 43.Accordingly, FIGS. 3-6 illustrate some exemplary embodiments of mountinga cutting member 20 to the balloon 16.

The first polymeric adhesive material 41 may be a high tensile strength,UV cured, medical grade adhesive with low ductility. For example, thefirst polymeric adhesive material 41 may have a tensile strength ofabout 2,500 psi or more, about 3,000 psi or more, or about 3,500 psi ormore. Furthermore, the percent elongation at break of the firstpolymeric adhesive material 41 may be about 12% or less, about 10% orless, or about 8% or less. For example, the percent elongation at breakof the first polymeric adhesive material 41 may be about 5% to about10%, or about 6% to about 7% in some instances. One suitable ultraviolet(UV) light curable polymeric adhesive material to use as the firstpolymeric adhesive material 41 is Loctite® 3943.

The second polymeric adhesive material 42 may be a relatively hightensile strength, UV cured, medical grade adhesive with high ductility.For example, the second polymeric adhesive material 42 may have atensile strength of about 2,500 psi or more, about 3,000 psi or more, orabout 3,500 psi or more. The ductility of the second polymeric adhesivematerial 42 may be greater than the ductility of the first polymericadhesive material 41. For example, the percent elongation at break ofthe second polymeric adhesive material 42 may be about 10 times or more,about 15 times or more, about 20 times or more, about 25 times or more,about 30 times or more, or about 35 times or more the percent elongationat break of the first polymeric adhesive material 41. For example, thepercent elongation at break of the second polymeric adhesive material 42may be about 100% or more, about 150% or more, about 200% or more, about225% or more, or about 250% or more. Thus, the second polymeric adhesivematerial 42 may be softer or more flexible than the first polymericadhesive material 41 (which may be harder or more rigid than the secondpolymeric adhesive material 41). One suitable ultraviolet (UV) lightcurable polymeric adhesive material for use as the second polymericadhesive material 42 is Loctite® 3321.

The combination of components used in the sub-assembly to secure thecutting member 20 to the balloon 16 may be chosen to provide specificstructural characteristics. For example, the first polymeric adhesivematerial 41, forming the mounting pad 40, may secure the cutting member20, while the second polymeric adhesive material 42, forming the base43, may readily adhere to the material of the balloon 16 and moreclosely match the radial and longitudinal growth of the balloon 16through inflation. For instance, the outside diameter of the balloon 16may increase by 4% or more, 6% or more, 8% or more, or 10% or more wheninflated to its rated burst pressure during use. Thus, it may bedesirable to select the second polymeric adhesive material 42 which hasa percent elongation at break which is greater than or equal to thepercent of radial growth of the balloon 16 when expanded to its ratedburst pressure (e.g., 10 ATM, 12 ATM, 15 ATM) to ensure that the base 43has sufficient ductility to stretch in accordance with the expansion ofthe balloon 16 when the balloon 16 is inflated. For example, a secondpolymeric adhesive material 42 having a percent elongation at break ofgreater than 12% may be chosen in some embodiments.

In one embodiment, shown in FIG. 3, the base portion 36 of the cuttingmember 20 may be embedded in the mounting pad 40 of the first polymericadhesive material 41 such that the first polymeric adhesive material 41is in contact with the lower surface 51, a first side surface 52, and asecond side surface 53 of the cutting member 20. Thus, the mounting pad40 may include a base portion 54 radially inward of the lower surface 51and first and second opposing wing portions 56, 58 extendingcircumferentially from the first and second side surfaces 52, 53,respectively. Although not shown in FIG. 3, the first polymeric adhesivematerial 41 may extend through openings 50 in the base portion 36(described further with respect to FIGS. 7 and 8) from the first sidesurface 52 to the second side surface 53 to help mechanically interlockthe mounting pad 40 to the cutting member 20.

The base 43 formed of the second polymeric adhesive material 42 may beadhesively bonded to both a surface of the mounting pad 40 and theexterior surface of the balloon 16. For instance, the base 43 mayinclude a layer 60 of the second polymeric adhesive material 42interposed between the lower surface of the mounting pad 40 and theexterior surface of the balloon 16 and adhesively bonded thereto, and/orthe base 43 may include first and second fillets 62, 64 of the secondpolymeric adhesive material 42 contacting and adhesively bonded toopposing side surfaces of the mounting pad 40 and the exterior surfaceof the balloon 16. In some instances, the fillets 62, 64 may include anangled surface angled at about 15°, about 30°, or about 45° to the lowersurface of the base 43.

In some instances, as shown in FIG. 3, a portion of the fillets 62, 64of the second polymeric adhesive material 42 may be located radiallyoutward of the opposing wing portions 56, 58 of the first polymericadhesive material 41 such that an imaginary line A extending radiallyoutward from the central longitudinal axis of the balloon 16 passesthrough both the first polymeric adhesive material 41 and the portion ofthe second polymeric adhesive material 42 located radially outward ofthe first polymeric adhesive material 41. Such a configuration, inaddition to the adhesive bond between the base 43 and the mounting pad40, may mechanically interlock the mounting pad 40 in the base 43 tohelp strengthen the securement of the base 43 to the mounting pad 40.

Another embodiment, shown in FIG. 4, may be similar to the embodimentshown in FIG. 3, with the inclusion of first and second reliefs 66located on opposing side surfaces 52, 53, respectively. In someinstances, the reliefs 66 may have a beveled, chamfered, or radiusededge extending between the cutting member 20 and one of the opposingwings 56, 58 of the mounting pad 40. Thus, the reliefs 66 may contactboth the mounting pad 40 and the cutting member 20, providing atransition at the interface between the cutting member 20 and the wingportions 56, 58 of the mounting pad 40. The reliefs 66, which may extendthe length of the cutting member 20, may be formed subsequent to castingthe cutting member 20 in the mounting pad 40. The reliefs 66 may beformed of the second polymeric adhesive material 42, or anotherpolymeric adhesive material if desired.

Another embodiment, shown in FIG. 5, may include a mounting pad 40similar to the embodiment shown in FIG. 3. However, as shown in FIG. 5,the base 43 formed of the second polymeric adhesive material 42 may beprovided on opposing sides of the cutting member 20 and the wingportions 56, 58 of the mounting pad 40 and covering the upper surface ofthe wing portions 56, 58. In such an embodiment, the base 43 may includefirst and second fillets 62, 64 of the second polymeric adhesivematerial 42 contacting and adhesively bonded to opposing side surfacesof the mounting pad 40 and the exterior surface of the balloon 16including a portion of the fillets 62, 64 of the second polymericadhesive material 42 located radially outward of the opposing wingportions 56, 58 of the first polymeric adhesive material 41 such that animaginary line A extending radially outward from the centrallongitudinal axis of the balloon 16 passes through both the firstpolymeric adhesive material 41 and the portion of the second polymericadhesive material 42 located radially outward of the first polymericadhesive material 41. Such a configuration, in addition to the adhesivebond between the base 43 and the mounting pad 40, may mechanicallyinterlock the mounting pad 40 in the base 43 to help strengthen thesecurement of the base 43 to the mounting pad 40. In some instances, thefillets 62, 64 may include an angled surface angled at about 15°, about17.5°, about 25°, about 30°, or about 45° to the lower surface of thebase 43. The base 43, shown in FIG. 5, may form a smooth, gradualtransition overlaying the mounting pad 40 from the side surfaces 52, 53of the cutting member 20 to the exterior surface of the balloon 16.

In the embodiment shown in FIG. 5, the lower surface of the mounting pad40 is shown in direct contact with the exterior surface of the balloon16. It is noted however that, although the embodiment shown in FIG. 5does not include a layer of the second polymeric adhesive material 42interposed between the lower surface of the mounting pad 40 and theexterior surface of the balloon 16, in some instances, a layer of thesecond polymeric adhesive material 42 may be included, similar to thatshown in FIG. 3, interposed between the lower surface of the mountingpad 40 and the surface of the balloon 16.

FIG. 6 is a top view of another embodiment of a cutting member 20adhesively mounted to the balloon 16. As shown in FIG. 6, thesubassembly for securing the cutting member 20 to the balloon 16 mayinclude opposing end portions 72 and an intermediate portion 70extending between the opposing end portions 72. As shown by thecross-section of FIG. 6A, taken along line 6A-6A of FIG. 6, theintermediate portion 70 may resemble that of the cross-section of theembodiment shown in FIG. 5. In other instances, the cross-section of theintermediate portion 70 may resemble that of the cross-section of theembodiment shown in FIG. 3 or FIG. 4, for example.

The cutting member 20 may have a width W1, the mounting pad 40 may havea width W2 greater than the width W1 of the cutting member 20, and thebase 43 may have a width W3 greater than the width W2 of the mountingpad 40. Width, as used herein, refers to the dimension transverse to thelongitudinal axis of the cutting member 20.

As shown in the enlarged view of FIG. 6B, an enlarged foot 74 formed ofthe second polymeric adhesive material 42 may be formed at the endportions 72 to enhance the bond to the surface of the balloon 16proximate the ends of the cutting member 20 to assure the end portions72 do not debond from the balloon 16 and lift away from the surface ofthe balloon 16. The enlarged foot 74 may have a width W4 greater thanthe width W3 of the base 43 throughout the intermediate portion 70 ofthe subassembly, thus increasing the bonding area of the secondpolymeric adhesive material 42 to the surface of the balloon 16proximate the end portions 72.

An exemplary method of mounting a cutting member 20 to a balloon 16 of aballoon catheter 10 will now be described with reference to FIGS. 7-12.As shown in FIG. 7, a cutting member 20 may be positioned in a mold 100having a cavity 102 formed therein. In some instances, the mold 100 maybe formed of a transparent or translucent silicone material, allowingultraviolet light to travel through the mold 100. The cutting member 20may be positioned with the cutting edge 38 facing into the mold 100 withthe base portion 36 exposed in the cavity 102.

Some of the other features of the cutting member 20 may also be seen inFIG. 7. For example, the base portion 36 of the cutting member 20 mayinclude series of alternating tabs 55 and openings 50 extending alongthe base portion 36 of the cutting member 20. The plurality of openings50 may extend through the base portion 36 from the first side surface 52to the second side surface 53 of the cutting member 20. The openings 50may open out to the lower surface 51 of the cutting member 20 in someinstances. The shape of the tabs 55 and openings 50 may vary. Forexample, in some instances the tabs 55 may have a shape similar to aninverted T-shape when viewed from the side or otherwise have a splayedpillar-like shape such that the portion of the openings 50 opening outto the lower surface 51 is narrower than another portion of the openings50 closer to the cutting edge 38. In other words, the width (in thelongitudinal direction) of the tabs 55 may be greater at or proximatethe lower surface 51 of the cutting member 20 than at a location closerto the cutting edge 38.

In addition to providing the cutting member 20 with a degree of lateralflexibility, the openings 50 between the tabs 55 may provide a locationfor the first polymeric adhesive material 41 to flow into as the baseportion 36 of the cutting member 20 is embedded into the first polymericadhesive material 41 during the molding process. Thus, the firstpolymeric adhesive material 41 may encapsulate the base portion 36,including the tabs 55 and extend through the openings 50 to mechanicallyinterlock the base portion 36 of the cutting member 20 in the mountingpad 40 to enhance the securement of the cutting member 20 in themounting pad 40.

The viscosity of the first polymeric adhesive material 41 may be chosenin the range of about 1,000 cP to about 15,000 cP, about 5,000 cP toabout 10,000 cP, or about 6,000 cP to about 7,000 cP at roomtemperature. A viscosity in this range may permit the first polymericadhesive material 41 to flow into the openings 50 while addressing otherconsiderations. Polymeric adhesive materials having low viscosities mayhave a tendency of lifting the cutting member 20 out of the mold 100during the molding process, whereas polymeric adhesive materials havinghigh viscosities may inhibit the ability to dispose the polymericadhesive material in the openings 50 without excessive air entrainment.

FIG. 8 is a cut-away perspective view of the cutting member 20positioned in the mold 100 prior to encapsulating the base portion 36 inthe mounting pad 40. The cutting edge 38 of the cutting member 20 mayextend into a slit 104 in the mold 100 to hold the cutting member 20 inan inverted position with the base portion 36 facing upward. As can beseen from the cross-section shown in FIG. 8, the shape of the cavity 102may correspond to the shape of the mounting pad 40 to be cast around thebase portion 36 of the cutting member 20. The lower surface 51 of thecutting member 20 (facing upward) may be positioned lower than the uppersurface of the mold 100 such that a layer of the first polymericadhesive material 41 may be formed across the lower surface 51, or thelower surface 51 of the cutting member 20 may be positioned flush withthe upper surface of the mold 100.

The cutting member 20, positioned in the mold 100, may then be placed inan oven and heated to an elevated temperature. For example, the cuttingmember 20 and mold 100 may be placed in an oven heated to about 30° C.,about 40° C., or about 50° C., for 30 minutes or more.

With the cutting member 20 heated to an elevated temperature, the firstpolymeric adhesive material 41 may be applied with an applicator in thecavity 102 adjacent the base portion 36 of the cutting member 20. Thefirst polymeric adhesive material 41 may be disposed in the cavity 102on each side of the cutting member 20 and forced through the openings 50in the base portion 36 to fill or substantially fill the cavity 102. Thecross-sectional view of FIG. 9 illustrates the cavity 102 filled withthe first polymeric adhesive material 41 to cast the mounting pad 40around the base portion 36 of the cutting member 20. Once the cavity 102has been filled with the first polymeric adhesive material 41, a film106, such as a transparent silicone film, may be placed over the cavity102.

The first polymeric adhesive material 41 may then be cured to cast themounting pad 40 onto the base portion 36 of the cutting member 20. Forexample, if the first polymeric adhesive material 41 is a UV curableadhesive, the first polymeric adhesive material 41 may be exposed toultraviolet light to initiate polymerization and cure the firstpolymeric adhesive material 41. To cure the first polymeric adhesivematerial 41, the mold 100, with the first polymeric adhesive material 41disposed in the cavity 102 around the base portion 36 of the cuttingmember 20, may be passed through an exposure tunnel 110, such as aLoctite® Zeta 7610 exposure tunnel, shown in FIGS. 10A-10C. One or morepasses may be made to cure the first polymeric adhesive material 41. Thespeed of the conveyor 112 may be set to expose the first polymericadhesive material 41 to ultraviolet light for a desired duration of timeper pass. For example, the speed of the conveyor 112 of the exposuretunnel 110 may be set to expose the first polymeric adhesive material 41to ultraviolet light for 60 seconds, 70 seconds, 80 seconds, or 90seconds per pass in some instances.

The mold 100, with the first polymeric adhesive material 41 disposed inthe cavity 102 around the base portion 36 of the cutting member 20, maybe passed through the exposure tunnel 110 during a first pass with thebase portion 36 of the cutting member 20 facing upward, and thus thecutting edge 38 facing downward, as shown in FIG. 10A. The cast blade108 (i.e., the mounting pad 40 with the cutting member 20 encasedtherein) may then be removed from the mold 100, with the film 106retained with the cast blade 108. The cast blade 108 may then be rotatedsuch that the cast blade 108 is setting on the film 106 with the cuttingedge 38 of the cutting member 20 facing upward. The cast blade 108 maythen be passed through the exposure tunnel 110 for a second pass withthe base portion 36 of the cutting member 20 facing downward and thecutting edge 38 facing upward, as shown in FIG. 10B. The speed of theconveyor 112 of the exposure tunnel 110 may be set at the same speed asthe first pass, or the speed may be changed. The film 106 may then beremoved from the cast blade 108 and the exposure process may be repeatedagain. For example, the cast blade 108 may then be passed through theexposure tunnel 110 for a third pass with the base portion 36 of thecutting member 20 facing upward and the cutting edge 38 facing downward,as shown in FIG. 10C. The speed of the conveyor 112 of the exposuretunnel 110 may be set at the same speed as the first and/or second pass,or the speed may be changed.

In some instances, the cutting member 20 may include a bridge 44coupling a first segment 46 of the cutting member 20 with a secondsegment 48 of the cutting member 20, as shown in FIG. 7. The bridge 44may be configured to fracture, separating the first segment 46 from thesecond segment 48 to increase the flexibility of the cutting member 20,as described in U.S. Pat. No. 7,291,158, incorporated by referenceherein. The fractured portion of the bridge 44 may be embedded in themounting pad 40, shielding tissue from unintentional damage from contactwith the fractured portions. The bridge 44 may be fractured prior to useor during the use of the cutting balloon catheter 10 in a medicalprocedure. In some instances, the bridge 44 may be fractured prior tomounting the cast blade 108 onto the balloon 16.

It may be desirable that the first polymeric adhesive material 41 has apercent elongation at break of 5% or more to ensure the first polymericadhesive material 41 has sufficient ductility to accommodate stretchingof the mounting pad 40 as the first segment 46 is bent relative to thesecond segment 48 to fracture the bridge 44. Polymeric adhesivematerials having an elongation at break of less than 5% may not besufficiently ductile, thus portions of the polymeric adhesive materialmay break away from the tabs 55 and openings 50 of the base portion 36of the cutting members 20 as the first segment 46 is bent relative tothe second segment 48.

After the first polymeric adhesive material 41 has cured to cast thecutting member 20 in the mounting pad 40, the cast blade 108 may beadhesively bonded to the exterior surface of the balloon 16 with thesecond polymeric adhesive material 42. For example, the balloon 16 maybe placed in a fixture and inflated to a desired mounting pressure, suchas about 60 psi, about 80 psi, or about 100 psi. The second polymericadhesive material 42 may be stamped onto the surface of the balloon 16in longitudinal strips, as shown in FIG. 11, and then the cast blade 108may be mounted thereto by pressing the mounting pad 40 into the strip ofthe second polymeric adhesive material 42. In other embodiments, thesecond polymeric adhesive material 42 may first be applied to themounting pad 40, and then the cast blade 108, with the second polymericadhesive material 42 applied thereto, may be adhered to the exteriorsurface of the balloon 16. The mounting step may be repeated for eachcast blade 108 until the balloon 16 is fully populated with the desirednumber of cutting members 20.

As shown in FIG. 12, with the cutting members 20 held in place withsupports 122 of a mounting fixture 120, the second polymeric adhesivematerial 42, forming the base 43, may be cured to mount the cast blade108 onto the balloon 16. For example, if the second polymeric adhesivematerial 42 is a UV curable adhesive, the second polymeric adhesivematerial 42 may be exposed to ultraviolet light to initiatepolymerization and cure the second polymeric adhesive material 42. Tocure the second polymeric adhesive material 42, the mounting fixture120, with the second polymeric adhesive material 42 applied to theballoon 16 and cast blades 108 positioned thereon, may be subjected to asource of ultraviolet light. For example, UV wands 124, such as Loctite®Zeta 7735 exposure wands, may be positioned proximate the secondpolymeric adhesive material 42 and activated for a desired duration oftime, such as about 1 minute, about 2 minutes, or about 3 minutes. Insome instances, the mounting fixture 120 may be rotated, such as at aspeed of about 10 RPM to about 35 RPM, during the exposure process.Additionally, nitrogen may be discharged toward the second polymericadhesive material 42 during the exposure process to reduce the oxygeninhibition effect.

The balloon 16, with the cutting members 20 mounted thereon, may then beremoved from the mounting fixture 120. The balloon 16, with the cuttingmembers 20 mounted thereon, may then passed through the exposure tunnel110 to further expose the first and second polymeric adhesive materials41, 42, if desired. For example, the subassembly may be passed throughthe exposure tunnel 110 for one or more additional passes to expose thefirst and second polymeric adhesive materials 41, 42 to ultravioletlight for about 25 seconds, 30 seconds, or 35 seconds per pass. Thesubassembly may be rotated between passes to ensure all portions areexposed to the ultraviolet light.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departure in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

What is claimed is:
 1. A method of securing a cutting blade to a balloonof a balloon catheter, the method comprising: molding a mounting padformed of a first polymeric adhesive material about a base portion of acutting blade, such that base portion of the cutting blade is encased inthe mounting pad; and adhering the mounting pad, with the base portionof the cutting blade encased therein, to a surface of a balloon with asecond polymeric adhesive material having a ductility greater than thefirst polymeric adhesive material.
 2. The method of claim 1, wherein themolding step comprises: placing the cutting blade in a mold having acavity; injecting the first polymeric adhesive material in the cavity ofthe mold; and curing the first polymeric adhesive material throughexposure to ultraviolet light to form the mounting pad.
 3. The method ofclaim 2, wherein the curing step comprises: passing the mold with thecutting blade positioned therein and the first polymeric adhesivematerial in the cavity of the mold through an exposure tunnel for afirst pass; removing the cutting blade and mounting pad from the mold;and then passing the cutting blade and mounting pad through the exposuretunnel for a second pass.
 4. The method of claim 2, wherein the cuttingblade is placed in the mold such that a base portion of the cuttingblade is facing upward and positioned in the cavity.
 5. The method ofclaim 1, further comprising: exposing the first polymeric adhesivematerial to ultraviolet energy prior to adhering the mounting pad to thesurface of the balloon to cure the first polymeric adhesive material. 6.The method of claim 5, wherein the adhering step comprises: applying thesecond polymeric adhesive material to the surface of the balloon, then;bringing the mounting pad, with the base portion of the cutting bladeencased therein, into contact with the second polymeric adhesivematerial applied to the surface of the balloon.
 7. The method of claim6, further comprising: exposing the second polymeric adhesive materialto ultraviolet energy to cure the second polymeric adhesive material. 8.A method of securing a cutting blade to a balloon of a balloon catheter,the method comprising: applying a first polymeric adhesive materialabout a base portion of a cutting blade, such that base portion of thecutting blade is encased in the first polymeric adhesive material;exposing the first polymeric adhesive material to ultraviolet energy,with the base portion of the cutting blade encased therein, to cure thefirst polymeric adhesive material to form a mounting pad surrounding thebase portion of the cutting blade; adhering the mounting pad, with thebase portion of the cutting blade encased therein, to a surface of aballoon with a second polymeric adhesive material, wherein a portion ofthe second polymeric adhesive material is located radially outward ofthe first polymeric adhesive material such that an imaginary lineextending radially outward from a longitudinal axis of the balloonpasses through both the first polymeric adhesive material and theportion of the second polymeric adhesive material located radiallyoutward of the first polymeric adhesive material; and exposing thesecond polymeric adhesive material to ultraviolet energy to cure thesecond polymeric adhesive material to mount the cutting blade onto theballoon.
 9. The method of claim 8, wherein the second polymeric adhesivematerial is applied to the surface of the balloon prior to bringing themounting pad, with the base portion of the cutting blade encasedtherein, into contact with the second polymeric adhesive material. 10.The method of claim 8, wherein the second polymeric adhesive material isapplied to the mounting pad prior to bringing the second polymericadhesive material into contact with the surface of the balloon.
 11. Themethod of claim 8, wherein the step of exposing the second polymericadhesive material to ultraviolet energy includes positioning one or moreultraviolet (UV) wands proximate the second polymeric adhesive materialand activating the one or more ultraviolet (UV) wands for a duration oftime.
 12. The method of claim 8, wherein the step of exposing the firstpolymeric adhesive material to ultraviolet energy includes passing thefirst polymeric adhesive material, with the base portion of the cuttingblade encased therein, through an exposure tunnel.
 13. A method ofsecuring a cutting blade to a balloon of a balloon catheter, the methodcomprising: applying a first polymeric adhesive material about a baseportion of a cutting blade, such that base portion of the cutting bladeis encased in the first polymeric adhesive material; exposing the firstpolymeric adhesive material to ultraviolet energy, with the base portionof the cutting blade encased therein, to cure the first polymericadhesive material to form a mounting pad surrounding the base portion ofthe cutting blade; positioning the cutting blade, with the base portionof the cutting blade encased in the mounting pad, and a balloon in amounting fixture; applying a second polymeric adhesive material to oneof the mounting pad and the balloon; mounting the cutting blade, withthe second polymeric adhesive material interposed between the mountingpad and the balloon, to the balloon while the cutting blade and theballoon are positioned in the mounting fixture; and exposing the secondpolymeric adhesive material to ultraviolet energy to cure the secondpolymeric adhesive material, wherein the second polymeric adhesivematerial has a ductility greater than the ductility of the firstpolymeric adhesive material.
 14. The method of claim 13, wherein thesecond polymeric adhesive material is applied to a surface of theballoon prior to bringing the mounting pad, with the base portion of thecutting blade encased therein, into contact with the second polymericadhesive material.
 15. The method of claim 13, wherein the secondpolymeric adhesive material is applied to the mounting pad prior tobringing the second polymeric adhesive material into contact with asurface of the balloon.
 16. The method of claim 13, wherein the step ofexposing the second polymeric adhesive material to ultraviolet energyincludes positioning one or more ultraviolet (UV) wands proximate thesecond polymeric adhesive material and activating the one or moreultraviolet (UV) wands for a duration of time.
 17. The method of claim16, wherein the one or more ultraviolet (UV) wands are positionedproximate the second polymeric adhesive material while the cutting bladeand the balloon are positioned in the mounting fixture.
 18. The methodof claim 13, wherein the step of exposing the first polymeric adhesivematerial to ultraviolet energy includes passing the first polymericadhesive material, with the base portion of the cutting blade encasedtherein, through an exposure tunnel.